Cantilevered hole opener

ABSTRACT

A hole opener for enlarging the diameter of bore holes, having a plurality of cantilevered spindles (6) for supporting rotatably attached cutter shells (9) having hardened surfaces for cutting and crushing to widen the bore hole. The cutter shells are supported on an inner threaded journal (13) which permits a plurality of load bearing rollers or bearings (26) to facilitate rotational movement of the cutter. The hole opener is provided on a tubular body which is connected in a drill string and which provides jetting nozzles (4) to remove the cutting debris and return it to the earth&#39;s surface. The cantilevered support spindle (6), journal (13) and cutter shell (9) assembly permit flexible interchange of cutter faces and sizes to be available for use with the same hole opener body and different directions of travel of the body.

RELATED CASES

This application claims priority to my provisional patent application,Ser. No. 60/012,609, filed Mar. 1, 1996, and PCT application, Ser. No.PCT/IB97/00358, filed Feb. 28, 1997, for the same invention.

BACKGROUND OF INVENTION

This invention relates to hole openers, specifically to openers whichare designed to enlarge the diameter of drilled holes.

Drillers commonly have drilled holes and thereafter enlarged the holefor the intended purposes with hole openers and reamers which aredesigned to enlarge the diameter of the pilot hole or original borediameter. Most openers or reamers known to applicant are devices havingthe cutting surfaces mounted on support arms which are mounted on theopener body and having their radial axis directed inward to support therotating cutter head. The abrasion and load experienced by such bodieswears the outer surfaces of the support arms as the opener moves throughthe formation to be opened and ultimately may cause the support arms tofail.

The normal operating problems of conventional hole openers or reamers isexacerbated when drilling horizontal or near horizontal applications. Insuch situations, the load and wear characteristics on the support armsmay cause early and catastrophic failure of the arm structure and oftenresults in loss of cutters in the borehole itself. Additionally, inhorizontal or near horizontal applications, the support arms ofconventional openers create additional torque on the tubular stringwhich carries the hole opener body. These problems may cause failure ofboth the support arms and loss of cutters in the hole requiringexpensive retrieval operations and delay the completion of theoperation.

Other economical considerations warrant consideration. In conventionalhole openers, the hole opener body is limited by its design toessentially one-size of diameter. The design of the conventional holeopener does not permit alternative sizes of holes to be made with thesame body because the span of the support arms fits only one size ofcutter. If alternative diameter holes are required, a whole new bodymust be acquired to open the hole. This requires additional trips intoand out of the hole to change the opener and cutter body. Additionally,conventional hole openers are designed to operate in pilot holes whichmust be provided to accommodate the large profile of the support arm andthe cutter. The larger pilot hole requires a larger size bit in theinitial drilling operation which is more costly to drill than one usinga smaller bit. Finally, changing the cutters on conventional holeopeners is time consuming, if it can be accomplished at all, and oftenrequires repair to the opener body and support arms due to damage causedby the pins and locking devices used to secure the cutters to theconventional opener body. Conventional openers typically have weldedsupport arms carrying the cutter and removal of the cutter would entailremoving the support arms and re-welding the new support arms afterreplacing the cutter itself. This extraordinary amount of work generallycauses the used or damaged conventional hole opener to be scrappedrather than repaired.

OBJECTS AND ADVANTAGES

Accordingly, several of the objects and advantages of the presentinvention may be readily appreciated from the disclosure of the presentinvention.

Since the present invention has eliminated the support arms whichpreviously supported the cutters, repair of the cutters when needed isaccomplished quickly and cheaply. Replacement of the existing size ofcutters with either larger or smaller cutters allows a single cutterbody to be used for many different size hole openings. The cost ofreplacing damaged cutters is significantly smaller than replacing thecomplete hole opener assembly. The diminished size of the body carryingthe cutters has significantly decreased the weight and portability ofthe hole opener. Conventional hole openers, because of their mass,require special handling to install and replace at the job site. Thepresent invention is compact and significantly lighter than theconventional devices permitting easy installation, removal andreplacement.

Another feature of the present invention is that only the cutters engagethe formation to be cut. Conventional cutters were supported by supportarms which supported the distal end of the cutter body. With the presentinvention, the cutter is supported by the cantilevered spindle whichmakes the profile of the cutter within the annulus more compact becausethere is no dragging of the support arm past the formation opened by thecutter. This feature also reduces the drag and torque on the body itselfand on the whole drill string thereby reducing mechanical wear on thedrilling assembly from this operation. The tubular member carrying thehole opener experiences less torque than prior conventional hole openersand requires less mechanical energy to open the hole to the desiredinner diameter.

Since the cutters may be interchanged to provide alternative cuttingsurfaces utilizing the same opener body, another feature of the presentinvention provides that numerous hole sizes may be accommodated with thesame opener body. This feature of the invention will allow a singleopener body to be taken to a job site and used throughout the drillingprocess and merely upgraded by replacement cutters having alternativecutting characteristics or alternative diameter cutting surfaces.

A still further benefit of the present invention is that it permits asmaller pilot hole to be used to provide the initial pathway for thedriller. Since the overall outer diameter profile of the opener body issmaller than conventional openers, a smaller and therefore moreeconomical pilot hole may be drilled. Drilling of a smaller pilot holemay be accomplished more quickly than drilling a larger diameter pilothole and may be accomplished by a smaller drilling rig which is alsomore economical.

Another advantage of the present invention can be appreciated becausethe worn cutters may be easily and quickly replaced by rig personnelwithout special tools or equipment by unscrewing the worn cutters andscrewing on the replacement cutters. With conventional hole openers andreamers, the whole assembly typically was returned to a central shop forrepair or replacement if worn cutters needed to be changed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective drawing of the use of a hole opener to enlargethe diameter of a hole which has been drilled under a body of water.

FIG. 2 is sectional drawing of a prior art device showing the relativedisplacement of the cutter arm, guide and cutter on the prior artdevice.

FIG. 3 is a sectional view of the preferred embodiment of the invention.

FIG. 4 is a sectional view of the preferred embodiment of the inventiontaken along line 4--4 of FIG. 3.

FIG. 5 is another plan view of the preferred embodiment of theinvention.

FIG. 5A is a schematic drawing of the preferred embodiment of theinvention disclosing the relationship of the spindle angle and thecutter face angle.

FIG. 6 is a partial sectional view of an alternative embodiment of theinvention disclosing the mounting of the cutter on a guide.

FIG. 7 is an axial view of an alternative embodiment of the inventionshowing an alternative type of cutter used on the invention.

BEST MODE FOR PRACTICING THE INVENTION

One form of the device of the present invention will be described indetail in operation. The use of the hole opener is illustrated in FIG. 1which discloses a river crossing operation wherein a pilot hole 90 hasbeen previously drilled by the drilling rig 91 and a larger diameterhole is desired. The hole opener is then engaged to open the holecreated by the pilot hole to the desired inner diameter. When theoperation is intended to burrow under a obstacle such as the river asdisclosed in FIG. 1, but which also may be a highway or otherobstruction, the hole opener of the present invention is small and lightenough to be threadably attached by hand and may be used either on theingress 92 of the tubular or the egress side 93 as the tubular member isbacked out of the initial pilot hole thereby saving additional time inthe overall drilling operation. It may be readily appreciated that theinvention disclosed herein may be used in any drilling operation,whether horizontal or vertical, and the choice of illustration in FIG. 1is not intended to limit the application to this type of drilling alone.The preferred embodiment of the present invention is more clearly setforth in FIGS. 3, 4 and 5.

FIG. 2 illustrates a typical prior art device used to open a drilledhole. The reamer is threadably engaged to a drill string by means of thepin 100 and box end 100 and lowered into the well bore. The pilot guide94 directs and centralizes the reamer in the hole and the cutter 95engages the surface to be enlarged. The cutter 95 is supported on a pin96' carried by the support arm member 96. As the cutter 95 is turned tocut or crush the surface to be opened, the jetting arrangement 97 clearsthe crushed materials from around the cutter face and the cutting debrisis lifted in the annular space-by this fluid flow. Following the supportarm is a circumferentially spaced wear ring 98 which is tipped with ahardened face, such as carbide facing, which rides on the annular spaceopened by the cutter to provide stability for the cutter and providelateral support for the critical support arm 96.

As the abrasive materials flow back past the support arm, the arm itselfwears and will sometimes fail allowing the cutter to become dislodged inthe hole and greatly increasing the time required to retrieve the bodyand the dislodged parts. Even angular movement of the pin 96' in theworn support arm will subject the cutter to substantial forces and causefailure. The prior art device shown in FIG. 2 is typical of prior artreamers and hole openers.

As shown in FIG. 3, the preferred embodiment of the present invention isfashioned on a tubular member or body 1 which is provided with standardthreaded box 5 and pin 7 for attachment in a drill string to enable itto be either pushed or pulled through the well bore as desired ornecessary. The tubular member 1 receives in operation drilling fluidstherethrough to be circulated into the well bore and then pumped out ofthe well bore and back to the earth's surface along with the cuttingsresulting from the opening operation. As further shown in FIGS. 3-4, thehole opener body 1 is fashioned on a tubular member and provides aplurality of nozzle ports 3 and nozzles 4 interposed between cuttershells 9 to deliver jetting circulation to clean the debris from thewell bore. Jet nozzle 4 may be changed to accommodate a variety of pumpcapacities and hydraulic programs. It may also be appreciated by oneskilled in the art that the present invention may also be used in airdrilling operations and the jet nozzle may be modified to accomplish airblast nozzles to clean debris from the well bore.

The member or body 1 as well as the cutter shells 9 are formed of anysuitable high strength steel which is well known to those skilled in theart. The cutters may assume any suitable configuration to accomplish thedesired results; but preferably include a bottom surface representedgenerally at 2 which, when the cutter elements are positioned on thesupport spindles 6 which project or extend outwardly therefrom as shown.

The cutter elements, cutter body and load bearing elements are supportedon a plurality of cantilevered support spindles 6 integrally formed onthe tubular body 1, or fixedly attached to the tubular body 1 as bywelding to form an integral body, at an angle in order that the cutterelements 11 may be exposed to the formation in the desired manner.

As disclosed in FIG. 3, hole opener 1 is fashioned from a tubular blankonto which is fashioned a plurality of cantilevered support shafts 6which are machined to accept the individual cutter body journal 13.Outwardly from the recessed surface 10, the cantilevered support spindle6 is threaded to receive the cutter body journal 13 and machined toprovide a lock means 29 to prevent the cutter body journal 13 fromdisengaging from the support spindle 6 during operation.

The cutter body journal 13 supports the cutter shell 9 which providesthe matrix onto which the hardened cutter buttons 11 are attached. Thecutter shell is fabricated to allow an outer ball bearing race 24 and aplurality of ball bearings 26, which provide load bearing capacity bothlongitudinally and laterally. A second ball bearing race 19 andplurality of ball bearings 21 provide additional load bearing capacity.

By further reference to FIG. 3, the cutter shell 9 and cutting surface 2is guided into the pilot hole with pilot guide 50 which centralizes thecutter body within the pilot hole which is to be enlarged. Cutter bodyshell 9 is rotatably attached to the cantilevered support spindle 6 anddisposed on cutter body journal 13 which is threadably attached to thesupport spindle 6. Cutter body journal 13 provides a plurality of loadbearing support means to provide rotatable support to the cutter body 9in the form of roller or ball bearing races. Cutter body journal 13 issealed to provide protection to the bearing surfaces by seal means at 15and 17. The seal means are standard elastomeric O-rings or other sealmeans well known to those skilled in the art.

FIG. 4 illustrates the axial view of the preferred embodiment of thepresent invention along the line 4--4 of FIG. 3 showing three cutters onthe member 1, but such number is purely for purposes of illustrationonly. For example, when a hole opener is employed to enlarge a well borefrom six inches to twelve inches, three cutter bodies 2 may be employed,but where the hole is to be enlarged from seventeen and a half inches totwenty inches, the number of cutter bodies by way of example only, maybe four or five, but any other number may be employed to accomplish thedesired results.

The cutting surfaces 2 are disposed to provide the enlargement of thehole and provide the maximum pathway for clearing the cutting debrisfrom the well bore.

As illustrated in FIG. 5, the cutter body journal 13 and cutter shell 9is supported on the cantilevered support spindle 6 by several loadbearing means 21, 26. The cutter body journal 13, as shown in FIG. 5,provides an inner ball race 19 and ball bearings 21, and outer journalball bearing race 24 and ball bearings 26. The cantilevered supportspindle 6 may be either integrally fashioned from the tubular member orbody 1 or by welding a support spindle into a recessed area of thetubular body 1 by techniques well known to those skilled in the art.Additional roller bearing members (not shown) may be provided betweenthe inner ball bearing race 19 and the seal means 15. The manner andmethod of placement of these additional bearings is shown generally at25 in FIG. 6.

The cantilevered support spindle 6 shown in FIG. 5 is conical andthreaded to engage the cutter journal 13. The support spindle 6 in thepreferred embodiment further provides a recess 29 which is eccentric ofthe principal axis of the support spindle to provide locking engagementwith hexagonal lock plug 36. The lock plug 36 is secured within thejournal 13 by retainer ring 33 which snap seats in recessed groove 35.Support spindle 6 is angled from a line perpendicular to the cutter body1 at an angle ranging from 15° to 25°. The preferred embodiment spindleis angled at 20° from a line perpendicular to the central longitudinalaxis of the tool body 1. Journal 13 further provides an eccentrichexagonal recess 34 into which seats, upon assembly, lock plug 36.Recess 29 provides the seat for lock plug 36 which extends throughjournal 13 to eccentrically engage in support spindle 6 to preventbacking-off of the cutter 9 in operation.

The journal 13 of FIG. 5 provides recessed grooves 15 and 17 forelastomer O-rings 15' and 17' to prevent the ingress of abrasivematerials from the cutting environment and to retain the lubricantmaterials which are packed around the journal upon assembly. The journal13 further provides an outer ball bearing race 24 which provides loadbearing surfaces for both the longitudinal forces and the transverseforces experienced by the cutter in operation. A plurality of outer ballbearings 26 are loaded into the journal body upon assembly and beforeengagement with the cantilevered support spindle 6. An inner ballbearing race 19 and plurality of ball bearings 21 provide further loadbearing capacity for the cutter body. The inner ball bearings 21 areretained in the journal race by retainer plug 23 and are similarlyloaded into the journal body 13 prior to engagement with thecantilevered support spindle 6. An additional roller bearing (not shown)may be provided in another bearing race area between the inner ballbearing race and the lower O-ring groove 15; and may be assembled priorto engagement of the cutter body on the support spindle 6 in a mannersimilar to the ball bearings described herein and as more generallydescribed in FIG. 6 at 25.

In order to provide the ability to use the hole opener in eitherdirection, the cantilevered support spindle 6 may be threaded to accepteither right-hand threads or left-hand threads or both. The spindle maybe machined to accept both right and left hand threads permittingjournals having either right hand or left hand threads to be used whenusing the hole opener in the ingress manner or in the egress manner.

The dihedral cutting face 2 of the cutter shell 9 of FIG. 5 is fittedwith a plurality of tungsten carbide buttons 11 around the periphery ofthe shell. Carbide wear buttons 12 are located around and on the distaledges of the shell 9 to prevent undue wear from the lateral well borewall. The angle of the dihedral face is between 10° and 25° from thetangent to the outermost point on cutter face 2' and which is parallelto the axis of rotation of the support spindle 6. Although the preferredembodiment is shown as a dihedral face having an angle of 15° from thetangent to the outermost point of the cutter face 2', other angles andother generally arcuate forms may be provided to provide similar actionof the cutter face.

As shown in FIG. 5A, the angle of the dihedral cutting face A iscoordinated with the angle of the spindle B to provide the maximumamount of cutting surface, the most appropriate angle of contact withthe formation to be cut, and to provide clearance of the distal edge ofcutter 9 with the well bore WB. The diameter of cutter 9 must be set toallow the cutter to roll without galling or scuffing the outer well-borewall WB to minimize wear on the distal edge and prevent excessive torquefrom the cutter dragging along the external well bore face. In thepreferred embodiment, dihedral angle A is 15° and cantilevered supportspindle angle B is 20°.

As previously noted, the cutting elements illustrated in FIGS. 3, 4, and5 are shown as tungsten carbide buttons. If desired, cutter shell may beof any suitable configuration of hardened surface, such as, by way ofexample only, mill tooth such as shown in FIG. 7 at 11', which are wellknown to those in the art. Large mill tooth cutters are typically chosenfor soft or medium formations, with the carbide button arrangement shownin FIG. 5 for harder rock formations. The cutting faces of these shellsare formed of any suitable and well-known hard materials such as by wayof example only sintered tungsten carbide or polycrystalline diamondfacings. The choice and suitability of these materials is well known tothose skilled in this art.

FIGS. 6 and 7 illustrate an alternative form of the invention for use inlarger diameter holes and with an alternative form of cutter body. FIG.6 discloses a hole opener with cantilevered support spindle 6a attachedto the tubular member or body 1 by welding. The support spindle 6a isfurther supported on the body by pilot guide 50 and gusset 52 which areattached to the member 1 and to the support spindle 6a by welding. FIG.6 further discloses an alternative arrangement with the cutter journal13 providing a plurality of load bearing means, shown generally asincluding at least a row of roller bearings 25 and two ball bearingarrangements 21 and 26.

FIG. 6 further discloses an alternative form of jetting nozzle and portarrangement 4a which is fashioned by affixing said nozzles on the distalends of hollow members 5 welded to the body 1 which providebi-directional release of fluid from the annulus of the body 1 throughport 3' and nozzle 4' toward the adjacent cutter. The plurality ofjetting nozzle members are additionally supported on the body 1 byattachment to guide 50' which is hardfaced 51' to prevent excessivewear. Each nozzle member provides two separate fluid paths which aredirected at the adjacent cutters to provide lubrication and removal ofthe debris from the cutting process. FIG. 6 discloses a sectional viewalong the line 6'--6' for the nozzle member axis and along the line6"--6" for the cutter axis.

FIG. 7 discloses the alternative embodiment illustrated in the profileof FIG. 6 from an axial perspective and demonstrates a spatialarrangement of plurality of cutter support spindles 6a consisting offour separate spindles attached to the tubular member or body 1. FIG. 7further discloses a mill tooth cutter 11' as an alternative cutterarrangement to those described in FIGS. 3, 4, and 5. The cuttersdisclosed in FIG. 7 are interchangeable with the cutters shown in FIGS.3, 4, and 5. This interchangeability permits economical use of thetubular body for multiple applications. The mill tooth cutter crushesand gouges the formation with the cutting debris being carried away byfluid directed by the jet nozzle arrangements shown at 3' and 4' whichprovide the same debris removal force of fluid spray as those describedand shown in FIG. 3.

The cantilevered support spindle feature of the present inventionpermits the use of a variety of cutter shell sizes to be offered whichmay be used on the same tubular member or body 1. The width of thecutter shell can be increased thereby increasing the cutting diameter ofthe hole opener. Alternative load bearing capacities and modalities maybe offered by modifying or changing the journal 13 to provide more orfewer ball bearing races, more or fewer roller bearing surfaces.

The foregoing disclosure and description of the invention areillustrative and explanatory thereof, and various changes in size, shapeand materials as well as in the details of the illustrated constructionmay be made without departing from the spirit of the invention. Althoughthe description above contains many specific features, these should notbe construed as limiting the scope of the invention but as merelyproviding illustrations of some of the presently preferred embodimentsof the invention.

What is claimed is:
 1. A hole opener for widening the diameter of a borehole comprising:a tubular member having threaded connections on each endof said member for connection in a drill string; a plurality of integralcantilevered support spindles extending from the tubular member; aninterchangeable journal providing load bearing means connected to eachcantilevered support spindle on said tubular member; and, aninterchangeable cutter shell supported on each journal providinghardened surfaces for engaging a surface of the bore hole to be cut,wherein the journal and cutter shell on each cantilevered supportspindle may be changed to permit the opening of more than one hole sizeutilizing the same tubular member.
 2. The hole opener of claim 1 whereinthe tubular body provides a plurality of jetting nozzles interposedbetween the cantilevered support spindles.
 3. The hole opener of claim 1wherein each integral cantilevered support spindle extending from thetubular member is threaded for both right hand and left hand threads foruse with either a right hand thread cutter journal or a left hand cutterjournal.
 4. The hole opener of claim 1 wherein each cutter shell isformed with a dihedral cutting face.
 5. The hole opener of claim 4wherein each cutter shell is formed with a plurality of sinteredtungsten carbide buttons on each surface of the dihedral face.
 6. Thehole opener of claim 5 wherein the integral cantilevered support spindleis angled about 15-25° from a normal to the tubular member, and awayfrom the cutting surface, and the distal face of the dihedral cuttershell is angled about 10-25° from the axis of rotation of the cuttershell, whereby the cutter shell will roll without scuffing the outersurface of the hole being widened.
 7. The hole opener of claim 4 whereineach cutter shell is formed with a plurality of hardened buttons on eachsurface of the dihedral face.
 8. A hole opener for widening the diameterof a pilot hole comprising:a cutter support body for insertion in apilot hole by attachment between two sections of a drill string, aplurality of cantilevered support spindles permanently affixed to thecutter support body, an interchangeable cutter journal threadablyconnected to each cantilevered support spindle, an interchangeablecutter shell disposed on each cutter journal with suitable hardened faceto cut and crush the face of the formation and widen the diameter of thepilot hole, sealed load bearing and rolling means disposed between eachsaid journal and each said cutter shell on each said spindle to permitrotational and load bearing movement of the cutter shell.
 9. A holeopener for widening a large diameter bore hole comprising:a tubular bodythreadably connected at each end to a drill string providing a fluidpassage throughout its longitudinal axis, a plurality of threadedspindles circumferentially fixed on said body and individually supportedthereon by a permanently affixed pilot guide and gussett, aninterchangeable journal threadably engaging each spindle providing aplurality of bearing race surfaces on an outer surface of said journal,load and roller bearings engaging the journal and being supported on therace surface of said journal, an interchangeable cutter shell for eachjournal providing a rotating surface which provides a hardened surfacefor cutting and crushing the engagement surface of the well bore, aplurality of jetting nozzle members providing a path from the fluidpassage of the tubular body to a distal portion of such jetting nozzlemember and providing one or more ports for each such jetting nozzlemember with said jetting nozzle members being alternately affixed to thetubular member with the threaded spindles, to direct the flow of fluidtoward the engagement surface of the well bore, a jetting nozzle guiderigidly affixed to each jetting nozzle and to the tubular body.
 10. Thehole opener of claim 9 wherein the cutter shell is formed with ahardened face of a striated grooves for use in soft or unconsolidatedformations of rock.
 11. The hole opener of claim 9 wherein the guidessupporting each jetting nozzle and spindle are hard-faced to preventexcessive wear of the guide.
 12. A method for widening a bore hole inthe earth by rotating a tubular body having circumferentially spacedcantilevered spindles carrying rotatable cutting surfaces for cuttingand crushing the surface adjacent the bore hole of a previously drilledpilot hole, comprising the steps of:connecting the tubular body to adrill string with the cutting face being selected to face the directionof travel of the drill string from the ingress side of the pilot hole tothe egress side of the pilot hole; moving the tubular body into the borehole so that the rotatable cutting surfaces are in a position to contactthe bore hole to be widened; rotating, circulating, and providinglongitudinal movement of the drill string to engage, cut, and crush thebore hole.
 13. A method for widening a bore hole in the earth byrotating a tubular body having circumferentially spaced cantileveredspindles carrying rotatable cutting surfaces for cutting and crushingthe surface adjacent the bore hole of a previously drilled pilot holewith a drill string passing therethrough, comprising the stepsof:connecting the tubular body to the drill string with the cutting facebeing selected to face the direction of travel of the drill string fromthe egress side of the pilot hole to the ingress side of the pilot hole;moving the tubular body into the bore hole so that the rotatable cuttingsurfaces are in a position to contact the bore hole to be widened;rotating, circulating, and providing longitudinal movement of the drillstring to engage, cut, and crush the bore hole.